A cast-part modular exhaust manifold whose various modules are at least partially identical in shape is already known from U.S. Pat. No. 4,288,988 A. If one wants to ensure sufficiently high process reliability, the walls of cast parts will have to be relatively thick.
A branch socket of an exhaust manifold configured as a hinged shell is known from DE 101 49 381 A1. The sheet metal section is cut and then deep-drawn and trimmed. This is followed by a forming process so that the joining flanges can be welded in a final step. Therefore, multiple branch sockets would be produced as a one-piece component with an increased number of bulges in the deep-drawing process.
A two-shell modular exhaust manifold whose internal-pipe modules are configured as hydroformed parts is known from DE 103 28 027 A1. The modules can be connected to each other by means of close sliding fits or plug-type connectors (already known from DE 43 39 290 C2) and are welded to each other via the outer shell. The internal pipes and the outer shells can be easily connected by means of the close sliding fits. Concerning the outer shell, the close sliding fits ensure the compensation for production-related tolerances prior to welding so that a weldable cover of the outer shell is provided in any case. The various modules may be provided as elements of a modular system. The manifold formed in this way tapers starting from the first arc module, i.e., the cross-section of the pipe increases continuously. Therefore, however, modules having different shapes, i.e., not being identical in shape, are required for designing a manifold.
A two-shell modular exhaust manifold whose internal-pipe modules are configured as hydroformed parts is also known from DE 199 23 557 A1. Furthermore, the use of identical components for the internal manifold pipes is described, said parts making the production of a six-cylinder or eight-cylinder exhaust manifold from a four-cylinder exhaust manifold possible.
JP 9 296 725 A describes a cast-part modular exhaust manifold, wherein the manifold pipe modules to be connected have an overlapping contour configured for telescoping. Said overlapping contour or the additional use of a sliding element makes relative motions between the manifold pipe modules on account of thermal stress or thermal expansion possible. For this purpose, appropriate meander-shaped compensating sleeves or bellows sleeves are provided in the region of the aforementioned overlapping contour, said sleeves ensuring tightness between two interconnected modules on the one hand and compensation between the manifold pipe modules connected thereto on the other hand.